A far-right Colombian warlord participating in peace negotiations with the government has been killed by his own men, police said on Monday, in another bloody incident that could undermine the shaky talks. Miguel Arroyave and four of his bodyguards were killed in a gunfight with fellow members of the United Self-Defense Forces of Colombia, or AUC, in the southern province of Meta on Sunday, an official from the DAS detective force said. Arroyave was a top AUC negotiator in struggling peace talks, which the government hopes will lead to the disbanding of the 20,000-member outlaw force. He commanded about one-third of the AUC's illegal army. He was the third prominent far-right outlaw to be killed by former comrades this year. AUC founder Carlos Castano's execution-style killing in April pushed the talks to the breaking point. The negotiations are key to Colombian President Alvaro Uribe's plans to pacify a nation locked in a 40-year-old war claiming thousands of lives a year, and officials fear failure could spark a surge of violence. --more 2327 Local Time 2027 GMT